“Ziplines” are gravity-based cable rides generally used to transport people for various purposes including recreational thrill rides, forest canopy tours, challenge courses and rescue operations. A typical zipline includes a stranded steel wire cable or fibre rope suspended between two supports, platforms at each support for launching and landing riders, pulley blocks and harnesses to support and transport riders along the cable.
For example, FIG. 1 depicts a zipline system in which wire rope main cable 4 is suspended between supports 1A, 1B which may be constructed of wood, steel, aluminum or any other structurally suitable material. Trees or boulders may alternatively function as supports 1A, 1B. A launch platform 2A is constructed on or surrounding support 1A, and a landing platform 2B is constructed on or surrounding support 1B. Either or both of platforms 2A, 2B may be (and typically are) fixed or mounted at elevated locations on supports 1A, 1B respectively. Each platform 2A, 2B is equipped with a ramp or steps 3A, 3B respectively to assist in launching and landing of riders as explained below. Although not shown, platforms 2A, 2B are typically also equipped with suitable safety railings and access control gates. Platforms 2A, 2B may be suspended relative to supports 1A, 1B to facilitate raising or lowering of platforms 2A, 2B (e.g. via suitable motorized winches) in order to periodically adjust the tension of cable 4.
Rider 7 begins by donning a harness 6 supplied by the zipline operator. Harness 6 includes a short tether which is securely fastened to a pulley block 5. After donning harness 6, rider 7 ascends to launch platform 2A, where the zipline operator's personnel couple pulley block 5 to cable 4, such that pulley block 5 will roll smoothly along cable 4. Rider 7 descends launch steps 3A and is released under the control of the zipline operator's personnel. More particularly, pulley block 5 rolls along cable 4 toward landing platform 2B (i.e. from right to left as viewed in FIG. 1) with rider 7 suspended beneath cable 4 by harness 6.
Rider 7 must reach and be braked and arrested at landing platform 2B. If rider 7 is not properly braked upon arrival at landing platform 2B, the moving rider may collide with support 1B, with landing platform 2B or with persons or objects on landing platform 2B. If rider 7's motion is not properly arrested upon arrival at landing platform 2B, rider 7 may roll back down to the nadir of cable 4. Similarly, if rider 7 is not carried along cable 4 with sufficient velocity, rider 7 may slow down, stop short of landing platform 2B, and roll back down to the nadir of cable 4. In either case, the zipline operator's personnel must rescue rider 7 from the nadir of cable 4. The rescue technique is well known and straightforward, and need not be described here. But, to avoid potentially time-consuming and somewhat labour intensive rescue operations, the slope of cable 4 (the vertical distance between platforms 2A, 2B), the cable's sag (the vertical distance between cable 4 at mid-span and a chord drawn between supports 1A, 1B) and the cable's tension are preferably adjusted to achieve a reasonable transit time at sufficient velocity along cable 4 to enable rider 7 to reach landing platform 2B.
The prior art has evolved various zipline braking and motion-arrest techniques. In some cases (e.g. if the landing platform is between the supports, at the nadir of the cable) no braking system is needed-the rider is intentionally allowed to roll back down to and stop at the nadir of the cable, and dismounts there. Another brakeless technique requires the zipline operator's personnel to physically catch and hold the rider upon arrival at the landing platform. Some zipline operators attach a second “tag line” cable, separate from the main zipline cable, to the rider's support pulley block, for braking purposes. Other operators provide automatic and/or rider-controlled brakes.
This invention provides a braking system for braking a zipline rider upon arrival at a landing platform, for arresting the rider's motion to retain the rider at the landing platform and for hauling the rider up to the landing platform. Besides enhancing safety, this allows the zipline operator's personnel to deal with other zipline operational aspects.